Systems for integrally joining two pieces of material, such as sheet metal pieces, are known in the art. One such type of system is a welding system which may employ a laser beam or some other source of thermal energy for welding a first piece of stock to a second piece of stock. In such a system the movement of the tool may be automatically controlled by the system itself. That is, the coordinates of the two pieces of sheet material relative to local system coordinate axes may be programmed into the system, the system thereafter controlling the movement of the tool in accordance with the stored coordinates.
A problem that arises when a first piece of sheet material is oriented in a substantially perpendicular manner to a top surface of a second, supporting, piece of sheet material is that, due to the shape or dimensions of the material, the placement of the tool adjacent to the area to be welded may be extremely difficult or impossible to accomplish. In order to successfully join two such pieces of material it may be necessary to weld the perpendicularly disposed first piece to the supporting piece by applying heat to a back surface of the supporting piece. In order to accomplish a weld, the welding tool should be applied to the supporting piece opposite the joint between the first and the second pieces. As can be appreciated, if the vertically oriented piece has an irregular shape, such as a meandering or an undulating shape, the programming and subsequent positioning of the welding tool is made extremely difficult.
This problem of positioning is compounded by the requirement that the welding tool and the workpieces may be in motion relative one to another during the welding process. Furthermore, any misregistration between the welding tool and the joint to be welded may result in a blow through occurring in the supporting material, that is, the heat from the welding tool may burn a hole through the supporting piece of material if the tool is misaligned with the first piece of material. Such a hole may prove detrimental to the structural integrity of the workpiece and may result in the workpiece being unusable for its intended purpose. Even if a blow through does not occur, the resulting weld may be a cold weld.
It is thus one object of the present invention to provide a method and an apparatus for positioning a tool relative to a workpiece.
It is a further object of the present invention to provide for the positioning of a welding tool relative to a workpiece having a discontinuity defined by a joint between a first and a second piece of material which are desired to be joined together.
It is a further objective of the present invention to provide for the accurate alignment and positioning of a welding tool for joining a first and a second piece of thin sheet-like metal stock when the first piece of stock is orientated substantially perpendicularly to the second piece of stock.
It is still one further object of the present invention to provide for positioning a welding tool adjacent to a surface of a supporting piece of sheet metal stock opposite that of a joint between the supporting stock and a second piece of stock which is desired to be welded to the first piece of stock.